Helium degassing of water is well-known and routinely practiced in batch-type operations in many chemical laboratories. Small-scale or laboratory applications for the degassed water include its use in operating analytical equipment such as high performance liquid chromatographs, in electrochemical systems, pharmaceutical formulation dissolution testers, in clinical procedures, scientific determinations, and the like.
Most known apparatus and methods are directed towards batch-type operations, rather than continuous in view of serious problems encountered in the continuous degassification of liquids. More specifically, it is often difficult to insure that the continuously produced output effluent is substantially uniformly degassed within prescribed levels. Further, it is known that in batch-type operations, the stored degassed water for example oftentimes absorbs air as well as contaminants carried thereby unless special precautions are exercised.
Degassed water for use in larger scale applications include the processing and manufacturing of oxygen-sensitive compounds, and for injection (deoxygenated water) into structures in deep sea water in order to increase the extractable fraction of subsurface hydrocarbon resources therefrom, and the like. In the latter mentioned application, the substantially oxygen-free water to be injected reduces corrosion rates of affected metal parts and prevents the growth of aerobic bacteria which often impedes the flow of the extracted hydrocarbons from its source to the surface.
Other applications may require the removal of exygen from the water, but not total degassing thereof. Such applications can readily benefit from the apparatus of the present invention. Nitrogen however will replace helium as the displacement gas; the apparatus then functions as a water deoxygenator rather than a water degasser.
Other methods of degassing water are known but suffer from certain disadvantages. For example:
Vacuum degassing of water is not readily compatible with a continuous operation.
Vacuum with stirring is not an efficient method of effecting mass transfer of the dissolved gases from within the water to its surface.
Sonification aids in the degassifying process by enhancing gas nucleation but fails to remove the nucleated gases.
Batch sparging with helium is effective in degassing water but, by definition, is not a continuous process and consequently requires storage facilities for the degassed water as mentioned above as well as an extended start-up period.
Degassing by heating water to boiling is effective and amenable to the continuous production of degassed water. The continuous boiling of water however is very expensive and potentially hazardous.
In the present invention, undegassed water is sprayed or "atomized" into a chamber wherein helium gas is continuously introduced. The gases dissolved in the water to be degassed are displaced by helium, which is not soluble in water, to provide the degassed water.
A more detailed description of the invention follows with reference to the accompanying drawings.